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COMING SOON, THE COMET OF THE YEAR

COMING SOON, THE COMET OF THE YEAR: Astronomers are calling Comet 46P/Wirtanen the "comet of the year." Two months from now, on Dec. 16th, the kilometer-wide ball of dirty ice will come within 11.5 million km of Earth--making it one of the 10 closest-approaching comets of the Space Age. Comet 46P/Wirtanen will probably become a naked eye object for several weeks during the holidays.

Yasushi Aoshima of Ishikawa, Japan, took the picture using a 12-inch telescope. It shows the comet's green atmosphere which is, impressively, almost twice as wide as the planet Jupiter. The green color comes from diatomic carbon (C2)--a gaseous substance common in comet atmospheres that glows green in the near-vacuum of space.

At the moment, the integrated brightness of the comet is similar to a 10th magnitude star--that is, dim. However, forecasters expect it to brighten more than 200-fold by December. If current trends hold, 46P could ultimately reach magnitude +3, making it not a Great Comet but a very good one, visible to the unaided eye and an easy target for binoculars or small telescopes.

Comet Wirtanen passes through the inner solar system every 5.4 years. Right now it is near the orbit of Mars, and it is heading in our direction. Click on the image above to explore the comet's approach, courtesy of NASA/JPL.

New comet discovered which will be in our area between late Nov and early Dec. It will be closest to the Sun Dec 3-4, the comet in the OP will be closest to the sun on Dec 12th. It would be really cool if we had to comets visible at the same time. They're not sure if this one will be a naked eye object but it seems to be brightening.

http://spaceweather.com/archive.php?...ay=12&month=11
(fair use applies)
AMATEUR ASTRONOMERS FIND A BRIGHT NEW COMET: There's a new comet in the morning sky. Discovered just last week by three amateur astronomers--one in Arizona and two in Japan--Comet Machholz-Fujikawa-Iwamoto (C/2018 V1) has quadrupled in brightness over the past few days. "It is now glowing like a fuzzy 8th magnitude star in the constellation Virgo," reports Michael Jäger of Turmkogel, Austria, who photographed it on Nov. 11th:

"The discovery of a comet by amateur astronomers is a rare event nowadays because robotic Near-Earth-Object search programs usually catch them first," he says. "My special congratulations to the three discoverers."

Comet Machholz-Fujikawa-Iwamoto appears to be a first-time visitor to the inner solar system. It is plunging toward the sun on nearly-parabolic orbit that will take it just inside the orbit of Mercury. Closest approach to the sun (0.38 AU) is on Dec. 3-4; closest approach to Earth (0.67 AU) is Nov. 27th.

Fresh comets like this one are notoriously unpredictable. They can surge in brightness, seeming to promise a spectacular display, when suddenly they fizzle as fragile deposits of ice are exhausted by solar heat. No one knows if Comet Machholz-Fujikawa-Iwamoto will even become a naked eye object. At the moment it is an easy target for backyard telescopes with the promise of ... unpredictability. Stay tuned!

GO TO LINK FOR GRAPHICSAmateur Don Machholz Discovers His 12th Comet! (Updated)
Arizona comet hunter Don Machholz did it again! He discovered his 12th comet only two mornings ago. Set your alarm, grab your scope, and take a look.
By: Bob King | November 9, 2018

UPDATE (Nov. 11, 2018): Comet brightens and gets an official name. Scroll down for news and new maps

With all the automated searches busily looking for anything crawling across the sky, it's a wonder an amateur can still discover a comet. Yet that's exactly what happened on November 7.53 UT, when Arizona's Don Machholz, the most successful living visual comet hunter, visually picked up a new comet in Virgo near the break of dawn. Two Japanese observers — Shigehisa Fujikawa and Masayuki Iwamoto — independently spotted the object around the same time and potentially will have their autographs added to the comet's final, official name.

Let's hear it from the discoverer via his Twitter account:

"746 hours of searching since my last visual comet discovery in 2010 and on Nov. 7.53 UT I visually discovered my 12th comet and today it was confirmed!"

Congratulations, Don — you beat the robots!

For now, the comet has been given the temporary designations TCP J12192806-0211143 and DM001. According to early observations shared on the comets-ml mailing list, the new object is magnitude 10.2 with a moderately condensed 4' (arcminute) coma and a short tail extending west in position angle 264°. Lucky for us, the new visitor stands about 20° high just before the start of morning twilight in Virgo, quite close to the easy naked-eye star (and beautiful double!) Gamma (y) Virginis .

We don't have many more details on the comet because an accurate orbit is still being determined. I used current ephemerides to plot its position for the next couple mornings so as many people as possible can tote out a scope for a look. With the comet at 10th magnitude under reasonably dark skies, an 8-inch should show it no problem. We'll have an orbit In the next few days, after which time I'll post a chart for more extended viewing.

In the meantime, you can use these orbital elements, kindly provided by Reinder Bouma, in your sky mapping apps and programs to create your own charts:

It's unclear just when perihelion will be — I've seen estimates from late November to mid-December. We'll know soon as to whether this is a brand new object or the return of a long-lost periodic comet. Likely the former.

For more details, go to the Central Bureau for Astronomical Telegrams Transient Object Followup Reports and the Minor Planet Center's Possible Comet Confirmation Page, where you can select "DM001" and click ephemerides to get updated positions.

It's so exciting to have a new comet discovery, especially a visual one made by an amateur astronomer. I'm as eager as you to train my telescope on this new visitor. Clear skies!

** Update: (November 10th) I looked for the comet this morning (November 10.48 UT) and was surprised how easy it was see in my 10-inch f/4.5 Dob. I star-hopped to the position at 56× and bingo, there it was! I estimated magnitude 9.5 with a well-condensed (DC=5) coma 3.5' wide and a hint of a westward tail. A Swan Band filter modestly enhanced the comet's visibility. Using higher magnification I discerned a faint, a ~13-magnitude stellar nucleus. More observations of the comet reveal the perihelion date is likely December 3rd, when it will approach within about 56 million kilometers of the Sun.

** Update: (November 11th) The comet appears to be brightening, with some observers spotting it in 56-mm binoculars. Estimates range from magnitude 8.5 to as bright as 7.5. This is an easy object! And while you're out, don't forget to look low near the horizon just as twilight starts for a close pairing of Venus and Spica.

** Update: (November 11th) Our comet just got an orbit and official name: C/2018 V1 (Machholz-Fujikawa-Iwamoto). See map and caption below for more details.

Best comet of 2018 is approaching
By Deborah Byrd and Eddie Irizarry in Astronomy Essentials | Space | November 8, 2018

Comet 46P/Wirtanen isn’t bright in any absolute sense. It currently requires a telescope to be seen. But it’s getting brighter and might reach visibility to the eye alone before the end of 2018.

Have you heard about comet 46P/Wirtanen? It’s due to pass closest to our sun and Earth in December 2018. Comet Wirtanen is the brightest comet in the night sky now, visible not with the eye alone, but to astronomers with telescopes. In December 2018, comet Wirtanen might indeed become visible to the eye, at least from dark locations. Binoculars should surely show the comet, perhaps by that time with a hint of a characteristic comet tail. Wirtanen’s closest approach to the sun will be December 12, 2018, and its closest approach to Earth is just a few days later, on December 16. You’ll find some charts, and info on how to see it, below.

But first … how close will this comet come?

How close will comet Wirtanen come?

According to astronomers at the University of Maryland, this passage of comet Wirtanen near the Earth (near by comet standards, that is) will be the 10th closest approach of a comet in modern times.

At its closest to us, the comet will be about 30 times the moon’s distance (7.1 million miles, or 11.5 million km).

The record for the closest observed comet – for all of recorded history – goes to D/1770 L1 Lexell, which came at less than 6 times the Earth-moon distance in June, 1770.

Or, contrast Wirtanen’s closest appraoch – 30 times the moon’s distance, 7.1 million miles, or 11.5 million km – to another comet that swept relatively near us recently, 21P/Giacobini-Zinner, causing a brief outburst in this year’s Draconid meteor shower. Giacobini-Zinner swept closest to Earth on September 9-10, 2018, at 36 million miles (58 million km). That was the closest Giacobini-Zinner had come in 72 years!

So you see comets are elusive objects. They don’t come very close, usually, in any absolute sense. Still, this 2018 approach is a good one for comet Wirtanen. To understand why, you have to think of the comet, and Earth, in their orbits.

Comet Wirtanen belongs to the Jupiter family of comets. Its orbit brings the comet just outside of Earth’s orbit, to just inside of Jupiter’s path around the sun. Although it orbits our sun every 5.4 years, the 2018 pass is its closest since its discovery some 70 years ago by American astronomer Carl A. Wirtanen on January 17, 1948.

Since its discovery, the comet has approached Earth’s orbit a dozen times. However, as it happens, each time it swept in near our planet’s orbit, Earth was on the far side of the orbit, as seen in the following illustration:

Not so in 2018. At the 2018 encounter, the comet and Earth will be on the same side of Earth’s orbit, when the closest approach occurs:

How bright will the comet get? No one knows for certain. Comets are unpredictable by their nature. Estimates indicate Wirtanen might reach a visual magnitude of 3.5 to 6. That would place the comet clearly in the realm of visibility with the unaided eye (although diffuse objects like comets are tougher to see than the pinpoints of stars at comparable magnitudes).

Want to stay up-to-date on Wirtanen’s brightness? University of Maryland astronomers are providing updates on its current brightness.

The image below provides a mixture of observations so far – and predictions – for the brightness of comet Wirtanen when closest to Earth in December, 2018:

How can you see comet Wirtanen?

And, most importantly, will this comet be visible with the unaided eye? Some observers are already glimpsing the celestial visitor using binoculars. In early November, Wirtanen had a visual magnitude of 8, making it the brightest comet in our skies for the moment, but still not visible to the unaided eye.

By mid December, 46P/Wirtanen might reach a magnitude of 3.5 to 6, perhaps visible to the unaided eye as a faint, diffuse object from dark skies.

In December, binoculars and small telescopes should show a diffuse cometary atmosphere, which might appear considerably large for an object whose icy cometary nucleus, or core, is less than a mile (just 1.2 km) wide.

Will the comet show a tail? Due to the orientation in space of Earth and Wirtanen when the comet is closest, the ion tail will be behind the comet, not visible from Earth’s perspective. If 46P/Wirtanen develops a slight curved tail in the coming weeks, it should be barely detectable, easier to see in astrophotography than with the unaided eye.

Again – always – expect to get the best views and contrast through binoculars or a telescope, in a dark sky location, far from city lights.

No telescope or binoculars? Consider watching the comet online. On December 12 and 17, 2018 (around the closest approach of the comet to the sun and Earth), the Virtual Telescope Project will be showing comet Wirtanen live, online, for free. Click here for more information, and check out their poster for this event, below:

So comet 46P/Wirtanen might – or might not – meet your expectations. As always, if you take the time to watch it over some weeks, you’ll appreciate it more. There are some nice details here to appreciate.

For example, as you gaze at the comet, realize that its cometary atmosphere – or coma – is bigger, in an absolute sense, than the planet Jupiter.

As for how big the coma will appear in our sky … some estimates suggest it might be as big as the apparent diameter of the moon! Maybe even bigger. Since the outer area of this dim coma will be the faintest, astrophotography will be the best way of detecting how big it really is, especially by mid December.

Also, if you have optical aid, you might be able to discern this comet’s movement in front of the stars. In early November, the comet was approaching Earth at 21,251 miles per hour (34,200 km/h), or 9.5 km/s. By December, as the comet gets closer to us, Wirtanen will appear to gain speed. Careful observations of the comet – in particular with a small telescope – should let you perceive its motion relative to the stars, over about a 30-minute period.

And there is more…

By early December, sky enthusiasts observing comet 46P/Wirtanen with telescopes will occasionally see one or more slow-moving objects entering the same field of view as the comet. These objects will appear so slow, that they will look like asteroids. However, these are not space rocks. They are human-made satellites.

Between December 6 and 12, 2018, comet 46P/Wirtanen enters an area of the sky where, as seen from our perspective, there is an orbiting ring of some 450 active geostationary satellites.

The belt of meteorological, television and other communication satellites orbit our planet at about 22,236 miles (35,786 km) above Earth’s equator. As these satellites orbit our planet at the same speed that Earth rotates, geostationary satellites appear to be motionless, at a fixed position in the sky, thus explaining why the small satellite dishes on the roof of our houses are pointing at a fixed position.

Because they orbit so high above Earth, these satellites are illuminated by the sun most of the time.

Observers using telescopes with a small motor that tracks astronomical objects in the sky, compensating for the Earths’ rotation, will perceive the slow motion of these satellites passing in front of the comet and stars. The view will be similar to the one seen on this video:

If the object appears to cross the field of view in the telescope fairly fast, you are likely looking at a satellite in low-Earth orbit. But if the satellite is moving slowly and remains visible several seconds through the telescope, you are probably seeing one of many geostationary satellites that will be visible in the path of comet Wirtanen from early to mid-December.

Sometimes, geostationary satellites may be visible in groups of 3 or more.

Can you confirm you are looking at a geostationary satellite at the eyepiece? Yes. If you are a using a computerized or tracking telescope, center the slow-moving object in the field of view. Then turn off the telescope or tracking function. If it’s a geostationary satellite, it will remain centered and now all the stars will appear to slowly drift as Earth rotates.

Keep in mind that you might have to re-align the telescope to continue observing the comet or other astronomical objects. Have fun!

Bottom line: Comet Wirtanen will come closest to Earth in December. Comets are unpredictable, but it seems this one might at least offer good binocular views, and it’ll possibly be visible to the eye. Will it be more interesting than just a diffuse coma ball? Let’s see what’s in store for us!

Small but hyperactive Comet 46P/Wirtanen is approaching Earth and could soon become visible to the naked eye. On Dec. 16th, the kilometer-wide ball of dirty ice will be less than 11.5 million km away--making it one of the 10 closest-approaching comets of the Space Age. It already looks magnificent through amateur telescopes. On Nov. 26th, Gerald Rhemann took this picture using a 12-inch reflector in Farm Tivoli, Namibia:

"The comet is currently gliding through the southern constellation Fornax," says Rhemann. "If you look carefully at the image, you can see galaxy NGC 922 near the comet's head, and another galaxy ESO 479-2 on the left."

Rhemann says that the comet's emerald green atmosphere is 50 arcminutes wide. In other words--almost twice as wide as a full Moon. Its apparent diameter could double in the weeks ahead as the comet comes even closer. Because Wirtanen's brightness is spread over such a wide area, it is diluted just below the limit of naked eye visibility, with a current magnitude near +6.0. We don't yet know if the comet will ultimately become visible to the unaided eye--but it will certainly be an easy target for binoculars and backyard telescopes in December.

The nucleus of 46P/Wirtanen is small (~1 km) compared to greater comets such as Hale-Bopp (~30 km) and Halley (~15 km). It makes up for this deficit by hyperactivity. Recent measurements show that the core of 46P/Wirtanen is spinning once every 8.9 hours and spewing almost 1028 water molecules every second. This exceeds the expected production of such a small comet.

Comet Wirtanen passes through the inner solar system every 5.4 years. Right now it is just below the orbit of Earth, and the gap is narrowing. Click on the image above to explore the comet's approach, courtesy of NASA/JPL.

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